With more than 20 years in PHP and web design with HTML, CSS, and javascript, I might be qualified.
HOWEVER, no promises at this time.
The KB signature app has three main components. I've downloaded all of them to browse. There's the form you see, which is a very simple HTML page with lots of tables; the CSS file which gives it color, size, font, and other visual attributes; and the killer, some javascript code.
What the script code does is take each ASIN and use it to scrape the Amazon book page for an image. I don't know yet whether it takes the cover image as shown and downsizes it, or finds another cover file somewhere on the page or elsewhere in the Amazon environment. I'd have to get intimate with the code. The script then somehow adds the image to the forum database, giving it a unique identifier and name, and uses that to create the BBCODE you see in the window when you make it.
When you approve the results, the script translates your work into the appropriate web page code, inserting the affiliation code in the process.
There's a lot of other functionality in both the web page and the javascript to handle social network links, website links, reader progress, custom text, and other options. Also, there is the preview web page with three format options and its underlying script code.
This is not a simple undertaking and the guts of it truly belong to KBoards. That means a wholesale rewrite of the look-and-feel as well as the script.
I retired from doing this stuff because I want to write fiction. So, I'm only describing the scope of what this entails, with the caveat that Sanctum can't just copy the code without risking IP infringement.
A simpler approach would require you to provide your own links to book cover images located elsewhere on the web. Your private webpage or one of the image repositories offered for free. This method would avoid the Amazon scraping script and simply build the signature code from the URL you provide.
If I were to tackle the replication effort, I'd allocate it to a team of two: one person to redesign the user interface, the other to develop and test the underlying javascript. The two would have to work together in test.
And all done gratis, because Timothy has already invested enough in this thing.